sometimes I have tried to get a map from google Earth and then add map from disk. I then have to calibrate it. How do I know what lat and lon are AND where do I plug them into?

I have no idea what point 1 and point 2 mean in the calibration window.

Once or twice I did have the txt file when I could not get the background image but did get the cords in the txt file. I used that once and it was fairly close, but I was guessing as to where to put what .... where.

Step by step would be very helpful. Remember- concerning this procedure, many of you are brain surgeons.... I am just a pre med student......... therefore step by step and terms I can understand as a premed would be helpful. bob